220 



Organ of Vision. 



I 



Mi 



CRand. lacrym 

 accessor. Monro 



297. The Lachrymal Apparatus. 



In each orbit are two compound r a c e m o s e 1 a c li r y m a 1 glands, 

 Glandulae lacry males, not entirely distinct from each other; the larger, Glandula 

 innominata Galeni, lies in the lachrymal fossa of the external angular 

 process of the frontal bone; the smaller, Glandula lacrymalis accessoria 

 Monroi, in front of and below it. The ten fine excretory ducts open at the 

 Fornix conjunctivas. The tears, which, in the fornices are conveyed inwards, 

 collect in the sinus between Plica scmilunaris and Caruncula lacrymalis, in 

 the Lacus lacrymarum ; from here they find their way into the Puncta lacry- 

 malia, the minute orifices of the lachrymal canals; then into the Canaliculi 

 lacrymales ; thence into the lachrymal sac, Saccus lacrymalis s. Dacryocystis, 

 which is lodged in a deep groove formed by the lachrymal and superior 

 maxillary bones. The lachrymal sac leads into the membranous nasal 

 duct, Ductus naso-lachrymalis, which opens into the inferior meatus, at 

 the lateral wall of the nasal cavity, covered by the inferior turbinated 

 bone (see Fig. 291). 



In the orbit are seven muscles ; six move the eyeball, one the 

 upper eyelid. 



M. levator palpebrae superioris arises from the upper surface of the 

 sheath of the optic nerve, and is inserted below the upper border of 

 the orbit into the superior tarsal cartilage. 



